With increasing demands for communication, transmission apparatuses that are capable of performing high-speed transmission at 10 to 100 Gbps have been in widespread use. Each transmission apparatus includes interface cards for performing processing for transmitting main signals and a control card for controlling the interface cards. The interface cards and the control card are mounted in respective slots provided in a rack, which is a housing for the transmission apparatus.
Multiple types of interface card are available depending on the format of the main signals to be processed, the number of ports, a transmission capacity per port, and a hardware configuration (for example, a variation resulting from production discontinuation or modification of electronic components included in each interface card). Examples of the format of the main signals include formats based on SONET/SDH (Synchronous Optical NETwork/Synchronous Digital Hierarchy) and Ethernet (registered trademark).
The interface cards are equipped with field programmable gate arrays (FPGAs) that realize functions according to the aforementioned types. The FPGAs are devices in which a circuit is formed for operation through configuration according to circuit data stored in an external memory. Even for interface cards having the same function, there are cases in which the types of FPGA included in the interface cards are different from each other. This is because, upon production discontinuation or modification of the FPGAs, the design of the interface cards is changed and thus the FPGAs are replaced with other variants.
The circuit data for each FPGA is modified, for example, in order to add a function. Thus, circuit data for each interface card in operation in a communication service is updated, each time a function is added. When the circuit data is updated, the interface card obtains the circuit data from the control card through communication within the transmission apparatus. The control card downloads the circuit data for the FPGA from a data center (for example, a network management apparatus) through a communication line for monitor and control and causes the downloaded circuit data to be stored in a storage device, such as a memory, provided in the control card.
The speed (for example, 128 kbps) of a communication line for monitor and control is low. Thus, if download is executed each time the circuit data is to be updated, it takes a large amount of time. Accordingly, the control card downloads and holds pieces of circuit data for all types of interface card from the data center in advance, and sends the circuit data to the interface cards, each time update processing for the circuit data is performed. Since the communication speed (for example, 100 (Mbps)) of communication within the transmission apparatus is higher than the speed of the communication line for monitor and control, the time taken for updating the circuit data is reduced, and consequently, the time until a communication service is started is also reduced.
For example, Japanese Laid-open Patent Publication No. 2002-314579 discloses a communication apparatus having FPGAs for converting data into formats corresponding to various forms of processing. Japanese Laid-open Patent Publication No. 2008-227993 discloses a transmission apparatus having an FPGA in a signal processing unit for performing signal processing.
For example, according to advancement in the technologies and diversification of communication services, the number of types of interface card is increasing, and correspondingly, the number of types of circuit data is also increasing. However, the storage capacity of the storage device included in the control card is finite. Thus, there is also a concern that an increase in the number of types of circuit data results in a shortage of the storage capacity in the future.
To address the concern, it is conceivable to increase the storage capacity of the storage device. However, since an increase in the storage capacity involves changes to the hardware, the design of the control cards may be changed. Thus, when a new type of interface card is added, a problem arises in that the control card that is already in operation is to be replaced with a new control resulting from the design change. Such a problem is not only limited to the circuit data in the FPGAs but is also found in other types of data (such as program data).